BIOCEV, First Faculty of Medicine, Charles University, 25250 Vestec, Czech Republic.
Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
Molecules. 2021 Oct 29;26(21):6567. doi: 10.3390/molecules26216567.
Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from chromaffin cells of adrenal medulla or sympathetic or parasympathetic paraganglia, respectively. To identify new therapeutic targets, we performed a detailed membrane-focused proteomic analysis of five human paraganglioma (PGL) samples. Using the Pitchfork strategy, which combines specific enrichments of glycopeptides, hydrophobic transmembrane segments, and non-glycosylated extra-membrane peptides, we identified over 1800 integral membrane proteins (IMPs). We found 45 "tumor enriched" proteins, i.e., proteins identified in all five PGLs but not found in control chromaffin tissue. Among them, 18 IMPs were predicted to be localized on the cell surface, a preferred drug targeting site, including prostate-specific membrane antigen (PSMA), a well-established target for nuclear imaging and therapy of advanced prostate cancer. Using specific antibodies, we verified PSMA expression in 22 well-characterized human PPGL samples. Compared to control chromaffin tissue, PSMA was markedly overexpressed in high-risk PPGLs belonging to the established Cluster 1, which is characterized by worse clinical outcomes, pseudohypoxia, multiplicity, recurrence, and metastasis, specifically including and mutations. Using immunohistochemistry, we localized PSMA expression to tumor vasculature. Our study provides the first direct evidence of PSMA overexpression in PPGLs which could translate to therapeutic and diagnostic applications of anti-PSMA radio-conjugates in high-risk PPGLs.
嗜铬细胞瘤和副神经节瘤（PPGLs）是罕见的神经内分泌肿瘤，分别起源于肾上腺髓质的嗜铬细胞或交感或副交感副神经节。为了确定新的治疗靶点，我们对五个人类副神经节瘤（PGL）样本进行了详细的膜蛋白组学分析。使用 Pitchfork 策略，该策略结合了糖肽、疏水性跨膜片段和非糖基化的额外膜肽的特异性富集，我们鉴定了超过 1800 种完整的膜蛋白（IMP）。我们发现了 45 种“肿瘤富集”蛋白，即所有五个 PGL 中都鉴定到的但在对照嗜铬组织中未发现的蛋白。其中，18 种 IMP 被预测定位于细胞表面，这是药物靶向的首选部位，包括前列腺特异性膜抗原（PSMA），这是一种用于核成像和治疗晚期前列腺癌的成熟靶点。使用特异性抗体，我们在 22 个特征明确的人类 PPGL 样本中验证了 PSMA 的表达。与对照嗜铬组织相比，高风险 PPGLs（属于已建立的 Cluster 1）中 PSMA 明显过表达，Cluster 1 的特征是临床结局较差、假缺氧、多发性、复发和转移，特别是包括 和 突变。使用免疫组织化学，我们将 PSMA 表达定位于肿瘤血管。我们的研究首次直接证明了 PSMA 在 PPGLs 中的过表达，这可能转化为高风险 PPGLs 中抗 PSMA 放射性缀合物的治疗和诊断应用。
